What Viagra® does:

VIAGRA® belongs to a class of medicine called phosphodiesterase type 5 (PDE5) inhibitors. Following sexual stimulation, VIAGRA® works by helping to relax the blood vessels in your penis by allowing blood to flow into your penis. This results in improved erectile function.

When Viagra® should not be used:

• If you are taking any medicines containing nitrates in any form (oral, sublingual [under the tongue], skin patch, or by inhalation [spray]). Although VIAGRA® is used occasionally, nitrates must never be used. Nitrates are found in many prescription medicines that are used in the treatment of angina pectoris (chest pain due to heart disease), such as nitroglycerin, isosorbide mononitrate, or isosorbide dinitrate. If you do not understand what nitrates are, or are unsure about whether a medication you are taking is a “nitrate”, ask your doctor or pharmacist.

If you take VIAGRA® with nitrate containing medicines or any other nitrates (e.g., amyl nitrite “poppers”), your blood pressure could suddenly drop to a life-threatening level. You could get dizzy, faint, or even have a heart attack or stroke.

• If you have ever had an allergic reaction to sildenafil citrate or the nonmedicinal ingredients in VIAGRA®.
• VIAGRA® is not to be used in men for whom sexual activity is inadvisable.

This medicine has been prescribed for you personally and you should not pass it on to others. It may harm them, even if their symptoms are the same as yours.

BEFORE you use VIAGRA® talk to your doctor or pharmacist if you:

• have heart problems (irregular heartbeats, angina, chest pain or had a heart attack). If you have heart problems, ask your doctor if your heart is healthy enough to handle the extra strain of having sex. If you have chest pain, dizziness or nausea during sex, stop exerting yourself. You should not use nitrates, but you should seek immediate medical assistance.
• are 65 years of age or over
• have had a stroke
• have low blood pressure or uncontrolled high blood pressure
• have liver or kidney problems
• have sickle cell anemia (abnormality of the red blood cells), multiple myeloma (cancer of the bone marrow) or leukemia (cancer of the white blood cells)
• are allergic to sildenafil citrate or any of the other ingredients of VIAGRA® tablets
• have a deformed penis or Peyronie’s disease
• have ever had an erection that lasted more than 4 hours
• have stomach ulcers or other bleeding problems.
• have a rare inherited eye disease called retinitis pigmentosa
• Ever had temporary, decrease, or permanent loss of vision, including a condition called Non-Arteritic Anterior Ischemic Optic Neuropathy (NAION). The specific type of vision decrease or loss, called non-arteritic anterior ischemic optic neuropathy (NAION), seems to occur rarely when blood flow to the optic nerve is reduced or blocked. Vision decrease or loss may be partial or complete, in one or very occasionally both eyes. While in some cases the condition may improve over time, it can also be irreversible. Rare cases of central serous chorioretinopathy (serous detachment of the macula layers of the retina) have been reported.
• Rare but serious skin reactions of Stevens-Johnson’s Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) have been reported during the post-marketing period.

VIAGRA® is not recommended for use in children under 18 years of age and in women.

VIAGRA® does not protect against sexually transmitted diseases (STD), including Human Immunodeficiency Virus (HIV).

Alcohol consumption may decrease the ability to get an erection. Patients should know how to react to the drug before operating a motor vehicle or any machinery. If you are taking VIAGRA® and experience temporary, decrease, or permanent loss of vision, stop taking VIAGRA® and call your doctor.

In case of chest pain occurring during or after sexual activity you should not use nitrates, but you should seek immediate medical assistance. Sudden decrease or loss of hearing has been reported in a few number of post-marketing and clinical trial cases with the use of PDE5 inhibitors, including Viagra® citrate. It has not been established whether these are related directly to the use of these medications or to other factors. If you experience these symptoms, stop taking VIAGRA® and call your doctor.

Drugs that may interact with VIAGRA® include:

• any drugs that contain nitrates in any form (oral, sublingual [under the tongue], skin patch or by inhalation [spray]). Nitrates are found in many prescriptions that are used to treat angina pectoris (Chest pain due to heart disease). You should not take VIAGRA® if you are taking these drugs.
• alpha-blockers (drugs used to treat prostate problems or high blood pressure)
• ketoconazole or itraconazole (drugs used to treat fungal infections)
• erythromycin (a drug used to treat bacterial infections) ritonavir, saquinavir or other drugs for the treatment of HIV
• cimetidine (a drug generally used to treat duodenal or gastric problems)

Grapefruit juice may increase the levels of VIAGRA® in your blood.

SIDE EFFECTS AND WHAT TO DO ABOUT THEM

As with most drugs, VIAGRA® can cause some side effects. These effects are usually mild to moderate in nature and do not last for a long time.

The most common side effects are headache and facial flushing. Less commonly reported side effects are indigestion, dizziness, stuffy nose, effects on vision (including color tinge, increased brightness of light and blurred vision), seizure, seizure recurrence, sudden decrease or loss of hearing and transient global amnesia (temporary memory loss).

In extremely rare instances, a man may have an erection that lasts many hours. You should call a doctor immediately if you ever have an erection that lasts more than 4 hours.

Reports of sudden loss of vision have occurred rarely with the use of oral erectile dysfunction medications (PDE5 inhibitors). It has not been established whether these are related directly to the use of these medications or to other factors. There may be an increased risk to patients who have already experienced a condition called Non-Arteritic Anterior Ischemic Optic Neuropathy (NAION). You should stop taking VIAGRA® and consult your doctor if you experience a decrease in, or loss of, vision in one or both eyes.

Reports of serious skin reactions characterized by rash, blisters, peeling skin and pain, which require immediate medical attention, have also occurred rarely. You should stop taking VIAGRA® and consult your doctor if you experience such reactions.

If you notice any side effects not mentioned above, or any of the above-mentioned side effects persist or become bothersome, please contact your doctor or pharmacist.

Source: Pfizer Inc. Product Monograph